Lithium ion batteries can be charged by different techniques. CCCV (constant current, constant voltage) charging is the conventional method that is predominantly employed for charging the lithium ion batteries. A theoretical analysis of pulse charging using varying current amplitudes with the relaxation periods has shown reduction in the charging time without reaching lithium saturation over the period [1]. It is based on the concept of increasing surface concentration of lithium at initial stages and maintaining the concentration value close to the saturation.

The objective of this work is to experimentally investigate the impacts of varying current pulse amplitudes on the lithium ion battery materials. This method consists of constant width charging, rest period and the applied current is decreased as the charging progress. Implementing the pulsed currents of different amplitudes on cathodic (Lithium Iron Phosphate) and anodic (Graphite and Li ₄Ti₅O₁₂) half cells separately creates varied impacts on the electrode materials. The results of charging time and overall cycle life are then compared with conventional charging method.

Figures 1 and 2 show the constant current and a portion of pulsed current profile that are used in the analysis. In this experiment, pulsed current profile is controlled by varying the duty cycle, relaxation periods are included in between pulses and current amplitudes are reduced as the charging progress. EIS, SEM and XRD are used in analyzing the impacts of both the charging protocols on the lithium ion cells.

References:

[1] B. K. Purushothaman and U. Landau, “Rapid Charging of Lithium-Ion Batteries Using Pulsed Currents A Theoretical Analysis,” J. Electrochem. Soc., vol. 153, no. 3, pp. A533–A542, Mar. 2006.